darrell mankin , Aug 02, 2007; 08:25 p.m.
I have a Nikon D40X and when I set the image size to the highest (L) setting I
get 3872x2592. However, when I download it into Photoshop the same image size
only gets me approximately 8x12 inches at 300 dpi.
My question is, how do I get a 12x18 in. image and keep it at 300 dpi? Or does
it matter if it's less than 300? If I uncheck the "resample image", which is
set on bicubic and resize to 12x17 it changes the dpi to 216.
What's the best way to get a decent image at least 12x17 inches. I would like to
do a book that's 8x8 in. and I'd like to be able to spread the image over two
pages if I wanted to.
I'd appreciate any help. Thanks.
Sam Thompson , Aug 02, 2007; 08:43 p.m.
It doesn't really matter because when you send your image to a printer they will handle the resizing for you, which might be a better algorithm.
darrell mankin , Aug 02, 2007; 08:47 p.m.
It does matter to me because if I'm using their Photoshop template and they have to go in there and fix stuff after me I will get charged for it.
Thanks...
James Gaines 
, Aug 02, 2007; 09:02 p.m.
If you want to have the 3872x2592 pixel image to be 18x12 at 300 ppi, then you will have to resample the image to increase the number of pixels.
In Photoshop, starting with your size 3872x2592 at 72 pixels/inch then:
1. Use image>image size
At the image size window?uncheck ?resample image?
Set the long side at 18 and the short side will end up at 12.05 with
215.11 pixels/inch.
2. After this is completed then check the ?resample image? and change the method to ?bicubic smoother?. Then set the pixels/inch to 300.
3. This will cause the image to be resized to about 5400x3615
4. Click OK to complete the operation
This will resize the image as you wish, and you can continue to work on the image to crop the size to 18x12 and other image changes as you see fit.
Depending upon the printer used, the image may print just fine at the 215 pixel/inch.
I would search photo.net for other discussions on this.
Another variation is to resample the image in 10% increments to achieve the 300.
I would try both methods to see which does best for you.
Ellis Vener 
, Aug 02, 2007; 10:29 p.m.
3872x2592. However, when I download it into Photoshop the same image size only gets me approximately 8x12 inches at 300 dpi.
3872/300 dots per inch = 12.907 inches
2592/300 dots per inch = 8.64 inches
Its simple math.
...and Mr. Gaines has it essentially correct.
Hector Javkin 
, Aug 03, 2007; 09:57 a.m.
Why are the two steps necessary? Why can't you change both the dpi and the size in inches, and let PS handle it? I'm not complaining about the responses above, I'm really asking.
JC Uknz , Aug 03, 2007; 06:33 p.m.
You can Hector
The important bit is to set the dpi [to 300dpi preferably] before you set the required print size. In the case of a largish print the computer will then [interpolate/resample] invent pixels by comparing adjacent pixels to maintain the pixel count at 300dpi [or whatever you choose]. Done to excess it creates a blurry effect but if you are using most of what the camera took you should have no problems.
Some suggest that the process should be done in 10% stages which is rather laborious unless you have a programme to do it for you ...
darrell mankin , Aug 04, 2007; 08:04 a.m.
Thanks James. I did exactly that before but wasn't sure if it's alright to enlarge the image that way. However, I didn't see a difference in the image as far as blur. I guess as what JC says below - if done in excess it creates a blurry effect. And I've also tried the way JC did it. What is the difference between the two? Both achieved the same thing...
And Ellis, thanks for the math lesson ;)
JC Uknz , Aug 09, 2007; 04:15 a.m.
darrell ... with computers like skinning a cat there are numerous ways to do it :-)
